<!DOCTYPE html>
<html>
<head>
	<title></title>
	<style type="text/css">
		.box{
			width: 2000px;
			height: 800px;
			border: 4px solid green
			margin:0 auto;
		}
		.left{
			width: 842px;
			height: 800px;
			border: 1px solid blue

		}
		.right{
			width: 560px;
			height: 200px;
			border: 1px solid red
			
		}
		.a1{
			width: 100px;
			height: 400px;
			border: 1px solid black
			
		}
	</style>
</head>
<body>
<div class="box">
	<div class="left"></div>
	<div class="right"></div>
	<div class="a1"></div>
</body>
</html>